How to Caulk Baseboard Gaps

By
Lee Wallender
Lee Wallender
Lee Wallender

Lee has over two decades of hands-on experience remodeling, fixing, and improving homes, and has been providing home improvement advice for over 13 years.

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Updated on 10/28/23
Reviewed by
Deane Biermeier
Deane Biermeier
Reviewed by Deane Biermeier
Deane Biermeier is an expert contractor with nearly 30 years of experience in all types of home repair, maintenance, and remodeling. He is a certified lead carpenter and also holds a certification from the EPA. Deane is a member of The Spruce's Home Improvement Review Board.
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Fact checked by
Jessica Wrubel
Jessica Wrubel
Fact checked by Jessica Wrubel
Jessica Wrubel has an accomplished background as a writer and copy editor, working for various publications, newspapers and in public libraries assisting with reference, research and special projects. In addition to her journalism experience, she has been educating on health and wellness topics for over 15 years in and outside of the classroom.
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Caulking Baseboards to Seal the Gaps

Lee Rogers / Getty Images

In This Article
Project Overview
  • Total Time: 1 - 2 hrs
  • Yield: Caulk baseboard gaps in one room
  • Skill Level: Beginner
  • Estimated Cost: $10 to $20

Many baseboards with gaps either at the top, where the baseboard meets the wall, or the bottom, where the baseboard meets the floor. Baseboard gaps aren't just unattractive; they also allow drafts to enter the home. One solution is to apply caulk to the gaps.

When to Caulk Baseboards

Caulk baseboards when there is a gap at the top or at the bottom, and when that gap is 1/4-inch or less in width.

  • Bottom: Gaps between the bottom of the baseboard and the floor happen because floor joists sag and foundations settle. If the gaps are wide enough, they allow air infiltration and seriously impact your home's energy consumption. A bead of caulk blocks airflow.
  • Top: Gaps at the top of the baseboard happen because the baseboard does not hug the wall close enough. You can make the wall look smoother by running a continuous bead of caulk along the top of the baseboard, where it meets the wall.

Should You Caulk Baseboards?

Caulking the bottoms of the baseboards does stop airflow but it also adds caulk to your flooring, which can be difficult to scrape off later on. Plus, it's a look that many homeowners don't like. One way to close this gap is to install quarter-round or shoe molding. Quarter-round is thin enough that it bends to hug the contours of saggy floors.


1:50

Watch Now: How to Install Shoe Molding or Quarter-Round Molding

Before You Begin

Unless the caulk matches the color of the walls or baseboards, it should be a paintable caulk. Paintable caulks are acrylic-latex products that take paint as well. Silicone caulks shed paint.

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What You'll Need

Equipment / Tools

  • Caulking gun
  • Plastic caulk scraping tool
  • Putty knife
  • Shop vacuum
  • Latex gloves
  • Painter's tape
  • Clean, dry rags
  • Paint brush

Materials

  • Paintable caulk
  • TSP or mild detergent
  • Paint

Instructions

  1. Scrape the Joints

    Use a putty knife to scrape away dried paint or drywall compound from the wall and top of the baseboard. If caulking the bottoms, use the putty knife to gently scrape underneath the baseboards. If the baseboards already have caulk, scrape it away with a plastic caulk scraping tool.

  2. Clean the Joints

    Use the shop vacuum to remove the remaining debris, then clean the joints with tri-sodium phosphate (TSP) or a mild detergent mixed with warm water. Let the areas dry thoroughly.

  3. Protect the Floor

    If applying caulk to the bottoms of the baseboards, run painter's tape along the flooring parallel to the baseboards, about 1/8-inch away. This will protect the flooring from excess caulk and establish a sharp line.

  4. Apply Caulk

    Mount a tube of paintable caulk in a caulk gun, then run a long, steady bead along the top joint, where the baseboard meets the wall. The bead should normally be no more than about 1/8- to 1/4-inch in diameter.

    Repeat the process with the bottom joint, where the baseboard meets the floor. Make sure to force caulk into the joint to fill the gaps. As the caulk begins to set up, carefully remove the painter's tape.

  5. Smooth the Caulk

    Smooth the caulk by dipping your finger in a water bowl and running it along the wet bead. Periodically rinse off your finger to remove excess caulk. Apply enough pressure to force the caulk into the gaps, but avoid the urge to overwork the caulk with your finger.

    Tip

    A good caulk bead will have a slightly convex shape in the joint between the baseboard and wall.

  6. Allow to Dry

    Caulk may shrink slightly as it dries, sometimes creating pinhole-sized gaps. After the caulk has dried, examine it carefully and spot-fix gaps in the caulk.

  7. Apply Paint to Match

    Once the caulk dries, paint over the caulk bead to match the existing color. For perfect lines, you may need to paint both the walls and the baseboards with different paints.

When to Call a Professional

If the gaps are more than 1/4-inch wide, it's best to reinstall the baseboards or add quarter-round to the existing baseboards to close the gaps. Installing quarter-round trim is a do-it-yourself project. But installing new baseboards that are shaped to follow the contours of sagging flooring is a project best left in the hands of skilled professionals.

The Spruce uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

  1. Caulking. U.S. Department of Energy (DOE)

  2. Do-It-Yourself Home Energy Assessments. U.S. Department of Energy.